On circular knitting machines the yarn to be knitted is fed by means of thread guides. These thread guides are normally positioned within the zones where the needles are first lifted and are then lowered to catch the yarn and are at any rate maintained within at the highest level reached by the needles during their upward motion. It is however known that this position of the thread guides in respect to the needles may prevent a correct positioning of the yarn to be picked up by the needles. Such positioning may also create some problems of interference and wear of the needles themselves. These problems are inconveniences already arise when using latch needles where the moving latch is usually able to recover the yarn even if it is misplaced with such an arrangement the yarn is put into the latch of the relevant needle while it is moving downward to cast off the previous loop; however these problems are much worse when using compound needles without a latch to recover that position of an incoming yarn.